Oscillation suppression device and ship provided with the same

Abstract: A oscillation suppression device is provided for attenuating a oscillation of an object (10) to be controlled by a gyro torque of a control moment gyro having a flywheel rotating at a high speed. The oscillation suppression device includes an angular velocity detector (18) for detecting a oscillation angular velocity of the object (10) to be controlled; and control units (17; 25, 26; 30; 40; 50) connected to a gimbal shaft (14a) of the control moment gyro for controlling the angular velocity (ϑ) of the gimbal (14) of the control moment gyro so as to absorb an external torque generated in the object to be controlled, in response to the oscillation angular velocity (Φ) detected by the angular velocity detector (18).

Description: Field of the Invention The present invention relates to a oscillation suppression device applied to a small ship or a boat such as a leisure boat, a suspension type transportation machine such as a gondola, a suspension from a helicopter or the like. It also relates to a ship provided with the oscillation suppression device. Description of the Related Art In a conventional oscillation suppression device for suppressing a small ship such as a leisure boat, a drum brake or a generator is coupled to a gimbal shaft so that an angular velocity of the gimbal may be adjusted by the resistance of the drum brake or the generator. Fig. 14 shows an arrangement of the conventional oscillation suppression device. A flywheel 1 which constitutes the oscillation suppression device is connected to a flat type spin motor 2 through a spin shaft 9 and is rotated at a high speed (with an angular velocity Ω of the flywheel) by the spin motor 2. The flywheel 1 is supported by a gimbal 4 through spin system bearings 3a and 3b so as not to be prevented from rotating at a high speed. The gimbal 4 has the gimbal shaft 4a and rotates about the gimbal shaft 4a at an angular velocity . The gimbal shaft 4a is supported by support frames 6a and 6b through gimbal system bearings 5a and 5b so that the gimbal 4 is not prevented from rotating. Further, each support frame 6a, 6b is fixed to an object 10 to be suppressed in oscillation by the oscillation suppression device. The support frames 6a and 6b transmits a gyro torque Tψ generated by the rotation of the gimbal 4 to the object to be controlled for reducing the oscillation angular velocity Φ of the object to be controlled. A drum brake 7 or a generator 8 is connected to one end of the gimbal shaft 4a. The angular velocity  of the gimbal is controlled by the resistance of the drum brake 7 or the generator 8. Thus, the gyro torque Tψ is controlled and the oscillation angular velocity Φ of the object to be controlled is reduced. Namely, in the case of the angular velocity  of the gimbal is controlled by the drum brake 7, as shown in Fig. 15, the drum brake 7 is provided on the gimbal 4a of a control moment gyro so that the angular velocity  of the gimbal 4 is controlled by the frictional force of the drum brake 7. In the case where the drum brake 7 is used for controlling the angular velocity  of the gimbal 4, the brake torque to be applied to the gimbal shaft 4a may be kept constant. For this reason, it is impossible to finely control the oscillation relative to the oscillation angular velocity Φ of the object to be controlled. Also, since a frequency band of the oscillation for the object to be controlled is narrow, it is impossible to apply this system to the large amplitude oscillation. Also, if the drum brake 7 is used, it is difficult to remove dust, moisture or the like adhered to a surface of the drum brake 7, and the heat radiation from the frictional surface is not satisfactory. Accordingly, the maintenance is difficult to be carried out, which deteriorates its performance. On the other hand, in the case where the generator 8 is used for controlling the rotation of the gimbal shaft 4a, a load resistor having a predetermined resistor value is connected to a terminal of the generator 8 to be connected to the gimbal shaft 4a to impart a brake force to the rotation of the gimbal shaft 4a to thereby control the angular velocity  of the gimbal 4 as disclosed in Japanese Patent Application Laid-Open No. Hei 6-129484 filed by the present applicants and entitled "Rotary Oscillation Suppressing Device". However, in the case where the generator 8 is used to control the angular velocity  of the gimbal shaft 4a, since the resistor value of the resistor provided in the generator 8 is kept constant, the same problem as that of the case where the brake drum 7 is used as mentioned above would be encountered. OBJECTS OF THE INVENTION In view of the foregoing defects, an object of the present invention is to provide a oscillation suppression device which is capable of controlling an angular velocity  of a gimbal in response to an external turbulence imposed on the object to be controlled, and of suitably controlling even if the external turbulence would be changed while keeping the oscillation suppression effect. Another object of the invention is to provide a ship provided with the above-described oscillation suppression device. SUMMARY OF THE INVENTION According to the present invention, in order to attain the above-described and other objects, a oscillation suppression device for reducing the vibratory angular velocity of the object to be controlled by controlling the angular velocity of the gimbal to control the gyro torque and a ship provided with the oscillation suppression device are as follows: A oscillation suppression device comprises: a control moment gyro having a flywheel rotating at a high speed; angular velocity detecting means for detecting a oscillation angular velocity of an object to be controlled; and control means connected to a gimbal shaft of said control moment gyro for controlling the angular velocity of the gimbal of said control moment gyro so as to absorb an external torque generated in said object to be controlled, in response to the oscillation angular velocity detected by said angular velocity detecting means. An angular velocity detector is provided in advance to the object to be controlled for detecting the angular velocity of the object to be controlled due to an external turbulence or the like. The angular velocity signal in response to the detected angular velocity is fed to the control means. The control means changes the torque for braking the gimbal shaft in response to the received angular velocity signal to change the angular velocity of the gimbal. Thus, it is possible to control the angular velocity of the gimbal in response to the external turbulence of the gimbal. Also, according to the present invention, it is possible to adopt the device wherein the control means includes an electromagnetic brake connected to said gimbal shaft for braking the gimbal shaft, and an electromagnetic brake control means for controlling said electromagnetic brake in response to the angular velocity detected by the angular velocity detecting means. Thus, the swing angular velocity, detected by an angular velocity sensor, of the object to be controlled due to an external turbulence or the like is fed to the electromagnetic brake controller which controls an excited magnetic current to be fed to the electromagnetic brake in response to the received angular velocity signal. Thus, the brake torque of the electromagnetic brake is changed to brake the gimbal shaft in response to the angular velocity signal to change the angular velocity of the gimbal. Thus, it is possible to control the angular velocity of the gimbal in response to the external turbulence. Also, according to the present invention, it is possible to adopt the device wherein the control means includes a generator connected to said gimbal shaft for braking the gimbal shaft, a variable resistor connected to said generator, and a resistor value control means for controlling a resistor value of said variable resistor in response to the angular velocity detected by said angular detecting means. Thus, the angular velocity signal in response to the angular velocity detected by the angular velocity sensor is fed to the resistor controller which controls the resistor value of the variable resistor in response to the received angular velocity signal. The resistor value of the variable resistor is changed, and the resistance of the generator is changed to change the angular velocity of the gimbal connected to the generator. Thus, it is possible to control the angular velocity of the gimbal in response to the external turbulence. Also, according to the present invention, it is possible to adopt the device wherein said control means includes a disc brake for braking said gimbal shaft, said disc brake having a friction disc coupled to and fixed to said gimbal shaft and another friction disc coupled to a support frame that support said gimbal shaft through gimbal bearings. Thus, the disc brake operates in response to the angular velocity detected by the angular detecting means. The gimbal shaft is braked by the frictional force generated between the friction surfaces of the two friction discs to thereby control the angular velocity of the gimbal in response to the external turbulence. By adopting the disc brake, the structure of the friction brake for braking the gimbal shaft is simplified so that the function inspection may readily be performed. Also, in the worst case, it is possible to easily carry out the maintenance simply by replacing the friction discs. Furthermore, it is possible to suppress the adverse affect due to the heat generation by the frictional force upon braking. Also, according to the present invention, it is possible to adopt the device wherein said control means includes a powder brake for braking said gimbal shaft, said powder brake having a magnetic disc coupled and fixed to said gimbal shaft, permanent magnets and a magnetic viscous material sealed in a casing that is fixed to a support frame for supporting said gimbal shaft through gimbal bearings and that surrounds said magnetic disc through gaps. Thus, the magnetic flux of the magnetic disc and the magnetic viscous material is applied and the Coulomb friction force is applied to the rotational motion of the fixed disc to thereby control the angular velocity of the gimbal in response to the external turbulence. Also, by adopting the powder brake, the structure of the brake used as a braking resistance against the gimbal shaft is simplified so that the function inspection may readily be performed. Also, in the worst case, it is possible to easily carry out the maintenance simply by replacing magnetic discs. Also, according to the present invention, it is possible to adopt the device wherein said control means includes an oil damper for braking said gimbal shaft, said oil damper having a stirring disc coupled and fixed to said gimbal shaft and an oil sealed in a casing that is fixed to a support frame for supporting said gimbal shaft through gimbal bearings and that surrounds said stirring disc through small gaps. The gimbal shaft is braked by the resistance generated when the oil sealed within the oil casing is moved and passed through fine gaps between the oil casing and the stirring disc by the rotation of the stirring disc in response to the rotation of the gimbal shaft. It is thus possible to control the angular velocity of the gimbal in response to the external turbulence. Also, in the case where the oil damper (viscous damper) is used, the braking resistance for the gimbal shaft is not the Coulomb friction force but the braking resistance (viscous resistance) in proportion to the angular velocity of the gimbal shaft. Thus, there is no non-linear element. It is possible to enhance the performance of the device. As described above in detail, according to the oscillation suppression device of the present invention, in a control moment gyro having a flywheel rotating at a high speed, the brake which is the electromagnetic brake, the generator connected to the variable resistor, the disc brake, the powder brake, the oil damper or the like is connected to one end of the gimbal shaft. In the case where the electromagnetic brake is connected to the device, the load torque of the electromagnetic is controlled in response to the change of the external turbulence generated in the object to be controlled. In the case where the generator is connected thereto, the excited magnetic current to be fed to the generator is controlled in response to the change of the external turbulence. In the same manner, in the case where the disc brake, the powder brake or the oil damper is connected thereto, the equipment to which the component is connected is controlled in response to the change of the external turbulence to thereby control the angular velocity of the gimbal. It is therefore possible to avoid the degradation of the oscillation performance due to the generation of the external turbulence and the change thereof in the object to be controlled and to perform an effective oscillation suppressing control. Furthermore, it is possible to arrange the gimbal shaft of the control moment gyro of the above-described oscillation suppression device in parallel to the pitch axial direction of the ship in the ship. The above-described oscillation suppression device may be made compact and may be located in a limited narrow space. The invention may be applied to various boats (small leisure boats or leisure fishing boats) which oscillates or swings with waves at various frequency to thereby obtain comfortable boats with small oscillation. Also, a power drive of a battery is possible for the above-described oscillation suppression device. The invention may be applied to a small boat which has no power source (generator to be driven by internal combustion engine or like). In this case, the present invention exhibits the effect. Also, in the control of the rotational speed of the flywheel, an extra controller for the angular velocity of the gimbal which is unsuitable under the circumstance on the boat where the humidity and temperature are both high is dispensed with, to provide an inexpensive boat with high reliability. BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings: Fig. 1 is a schematic view showing a oscillation suppression device according to a first embodiment of the invention; Fig. 2 is a cross-sectional view of the first embodiment shown in Fig. 1; Fig. 3A is a block diagram showing a circuit for driving a spin motor applied to the embodiment shown in Fig. 1; Fig. 3B is a graph showing a relationship between the rotational speed and the torque; Fig. 4 is a schematic view showing a oscillation suppression device according to a second embodiment of the invention; Figs. 5A and 5B are schematic views showing a oscillation suppression device according to a third embodiment of the invention; Fig. 6A is a view showing a disc brake in accordance with the embodiment shown in Figs. 5A and 5B; Fig. 6B is a graph showing a braking characteristic of the disc brake shown in Fig. 6A; Fig. 7A is a view showing a powder brake in accordance with a fourth embodiment; Fig. 7B is a graph showing a braking characteristic of the powder brake shown in Fig. 7A; Figs. 8A and 8B are schematic views showing a oscillation suppression device according to a fifth embodiment of the invention; Fig. 9A is a view showing an oil damper in accordance with the embodiment shown in Figs. 8A and 8B; Fig. 9B is a graph showing a braking characteristic of the oil damper shown in Fig. 9A; Fig. 10 is a schematic view showing a oscillation suppression device according to a sixth embodiment of the invention; Fig. 11 is a graph showing the oscillation suppression effect and the brake force; Fig. 12A is a schematic fragmentary view showing a ship with the oscillation suppression device in accordance with the first embodiment of the invention; Fig. 12B is an enlarged view showing a part A of Fig. 12B; Fig. 13A is a view showing an example of an overall oscillation suppression device according to the invention; Fig. 13B is a cross-sectional view taken along the line A-A of Fig. 13A; Fig. 14 is a schematic view showing an example of a conventional oscillation suppression device; and Fig. 15 is a cross-sectional view showing another example of the conventional oscillation suppression device. DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described with reference to the accompanying drawings. In Fig. 1 which shows a oscillation suppression device according to a first embodiment of the invention, a flywheel 11 is connected to a flat type spin motor 12 through a spin shaft 12a and is rotated at a high angular velocity Ω by the spin motor 12. Namely, the rotational speed of the flywheel 11 is not controlled but the flywheel is always rotated at a fixed rotational speed with a balance with a loss by the rotational resistance. Accordingly, an extra controller is not required for controlling the rotational control. Thus, the number of electric and electronic components therefor is reduced to thereby enhance the reliability of the device and to reduce the cost therefor. A flat cylindrical spin motor 12 for rotating the flywheel 11 is used for the purpose of the compactness of the oscillation suppression device. Namely, as best shown in Fig. 2, the spin motor 12 is low in height so as to avoid the hindrance against the rotation of a gimbal 14. The spin motor 12 is composed of an armature 21, permanent magnets 24, brushes 22 and bearings 23. Since a printed motor is used for reducing the thickness of the armature 21, it is possible to make the motor compact in size. Figs. 3A and 3B are a block diagram showing an open control characteristic of the spin system for driving the spin motor and a rotational speed-torque characteristic. As shown in Fig. 3A, in the spin system, a constant voltage is supplied from a battery 12b and a current is supplied directly to the spin motor 12 through a current limiter 12c. The flywheel 11 is coupled directly with the spin motor 12. The feedback control by a rotational speed sensor for the spin motor 12 or the like is not adopted. The rotational speed is determined by a voltage constant characteristic line shown in Fig. 3(B) at a point P at a balance with the rotational torque (frictional loss, air wind loss, eddy current loss, copper loss or the like). The open control is adopted. Thus, it is possible to dispense with the rotational speed controller as described above. Also, the current limiter 12c prevents the eddy current from flowing upon the drive of the motor 12 to thereby avoid the damage of the motor 12. Turning back to Fig. 1, the flywheel 11 is supported by the gimbal 14 through the spin system bearings 13a and 13b to suppress a loss due to the rotational resistance and to avoid the reduction in high speed rotation. The gimbal 14 has the gimbal shaft 14a and rotates about the gimbal shaft 14a at an angular velocity . The gimbal shaft 14a is supported to the support frames 16a and 16b through the gimbal system bearings 15a and 15b so as not to obstruct the rotation of the gimbal 14. Furthermore, the support frames 16a and 16b are fixed to the boat 10 to be controlled and transmits the gyro torque Tψ generated by the rotation of the gimbal 14 to the boat 10. Also, the one end of the gimbal shaft 14a is connected to an electromagnetic brake 17 whereby the angular velocity  of the gimbal 14 is changed in response to the load torque of the electromagnetic brake 17. On the other hand, an angular velocity sensor 18 for detecting the oscillation angular velocity of the boat 10 is provided in advance in the boat 10. The angular velocity sensor 18 detects the oscillation angular velocity on the real time basis and feeds an angular velocity speed to an electromagnetic brake controller 19 in response to the detected angular velocity Φ. The latter 19 controls an excited magnetic current to be fed to the electromagnetic brake 17 in response to the received angular velocity signal. Thus, the load torque of the electromagnetic brake will change. The operation of the first embodiment will now be described. Now, let us assume that the flywheel 11 has been already rotated at a high speed rotational speed at an angular velocity Ω. When the boat 10 is subjected to a change in oscillation angular velocity Φ by the external turbulence or the like, the angular velocity sensor 18 detects the oscillation angular velocity Φ and the angular velocity signal is fed to the electromagnetic brake controller 19 which controls the excited magnetic current to be fed to the electromagnetic brake 17 in response to the received angular velocity signal. In this case, the electromagnetic brake controller 19 controls the excited magnetic current so that a gyro torque Tψ for reducing the oscillation angular velocity Φ of the object to be controlled is generated. In the electromagnetic brake 17, the load torque is changed in response to the excited magnetic current whereby the angular velocity  of the gimbal 14 will change. Thus, it is possible to avoid the degradation in control performance against the external turbulence of the object to be controlled and to perform an optimum suppression of the oscillation. In a second embodiment of the invention shown in Fig. 4, a generator 25 is connected to one end of the gimbal shaft 14a. A variable resistor 26 is connected to the generator 25 and the resistor value of the variable resistor 26 is changed by controlling a resistor controller 27. An angular velocity signal fed out from an angular velocity sensor 18 provided at a predetermined position is fed into the resistor controller 27 to thereby control the resistor value of the variable resistor 26 in response to the angular velocity signal. The operation of the second embodiment will now be described. Now, let us assume that the flywheel 11 has been already rotated at a high speed rotational speed at an angular velocity Ω. When the boat 10 is subjected to a change in oscillation angular velocity Φ by the external turbulence or the like, the angular velocity sensor 18 detect the oscillation angular speed to feed the angular velocity signal to the resistor controller 27. The resistor controller 27 controls the resistor value of the variable resistor 26 in response to the received angular velocity signal. In this case, the resistor controller 27 controls the resistor value so that a gyro torque Tψ for reducing the oscillation angular velocity Φ of the object to be controlled is generated. The generator 25 impart the load to the rotation of the gimbal shaft 14a in response to the resistor value of the variable resistor 26 whereby the angular velocity  of the gimbal 14 will change. In an oscillation suppressing device in accordance with a third embodiment of the present invention shown in Figs. 5A, 5B, 6A and 6B, a disc brake 30 is mounted as a brake for braking the oscillation of the gimbal shaft 14a. The disc brake 30 is composed of a friction disc 31 fixed to the gimbal shaft 14a and a friction disc 32 fixed to a support frame 16b as shown in Fig. 6A. The rotation of the gimbal 14a is braked by the frictional torque generated upon the frictional contact between the friction disc 32 fixed to the side of the support frame 16b and the friction disc 31 fixed to the gimbal 14a. A plurality of permanent magnets 33 and a braking plate 34 are arranged on the friction disc 32 fixed to the support frame 16b, and a magnetic flux caused by the permanent magnets is applied between the frictional disc 31 fixed to the gimbal shaft 14a and the frictional disc 32, whereby a Coulomb friction force acts against the rotational motion of the gimbal 14 to thereby suppress the oscillation of the gimbal 14. At this time, the braking force that is kept substantially constant may be obtained by the magnetic flux of the permanent magnets 33 as shown in Fig. 6B. However, the electromagnetic brake 17 used in the first embodiment may be used instead of the permanent magnets 33 so that the brake of the gimbal shaft 14 may be attained in the same manner as in the first embodiment. In an oscillation suppressing device in accordance with a fourth embodiment of the invention shown in Fig. 7A, a powder brake 40 is mounted as a brake for braking the oscillation of the gimbal shaft 14a. The powder brake 40 is composed of permanent magnets 41 provided on the support frame 16b, a magnetic disc 42 fixed to the gimbal shaft 14a, and magnetic viscous material (powder) 44 provided for surrounding the magnetic disc 42 by providing seals 46 at a through-portion of the gimbal shaft 14a and sealed within a casing 43 that is fixed to the support frame 16b. Then, the magnetic flux 45 caused by the permanent magnets 41 is applied to the magnetic viscous material 44 whereby the Coulomb friction force acts against the rotational motion of the gimbal 14 to thereby brake the oscillation of the gimbal 14. At this time, the brake force that may be kept constant may be obtained by the magnetic flux 45 of the permanent magnets 41 as shown in Fig. 7B. However, also in this embodiment, the electromagnets may be used instead of the permanent magnets 41 and the excited magnetic current to be supplied to the electromagnets is controlled. As a result, it is possible to control the angular velocity of the gimbal so as to absorb the turbulent torque generated in the object to be controlled. In an oscillation suppressing device in accordance with a fifth embodiment of the invention shown in Figs. 8A, 8B and 9A, an oil damper (viscous damper) 50 is used as a braking device for the gimbal shaft 14a. The feature of this embodiment is that the braking force in proportion to the gimbal angular velocity  is obtained in response to the rotation force generated in the gimbal shaft 14a. In the third and fourth embodiments, the frictional braking force is caused by the Coulomb friction force, but in this embodiment, the braking force is caused by the viscous friction. Accordingly, it is possible to ensure the higher performance than that of the third and fourth embodiments. The oil damper (viscous damper) 50 is formed as follows. As shown in Fig. 9A, an oil seal 52 is provided at a through-portion of the gimbal shaft 14a around the stirring disc 51 (see the cross-section B-B) that is fixed to the gimbal shaft 14a. An oil casing 53 which completely surrounds the stirring disc 51 is fixed to the support frame 16b. The interior of the oil casing 53 is filled with oil (silicone oil or the like) 54. The resistance caused when the oil 54 is passing through the fine gaps 55 formed between the casing 53 of the oil damper 50 and the disc 51 is used as the brake force of the gimbal shaft 14a to thereby brake the oscillation of the gimbal 14. At this time, the brake force of the oil damper 50 acts as the viscous friction in proportion to the angular velocity  as shown in Fig. 9B on the theoretical basis. Accordingly, it is possible to ensure the linear brake control, and it is easy to control the gimbal 14. In an oscillation suppressing device in accordance with a sixth embodiment of the present invention shown in Fig. 10, relating to the fifth embodiment shown in Figs. 8A and 8B or the third embodiment shown in Fig. 5A and 5B, it is possible to adjust the oscillation angular velocity of the gimbal 14 by using the disc brake 30 or the oil damper 50 as the brake at a low magnitude. According to this embodiment, since the component in the yawing axial direction even for one set of the oscillation suppressing device is small, it has an advantage that it is not always necessary to provide two devices for one set. Subsequently, Fig. 11 shows the relationship between the brake force for braking the gimbal shaft 14a described above and the oscillation suppression effect. As shown in the figure, in order to obtain the best oscillation suppression effect in the range of the optimum values of the brake force, it is necessary to adjust, in advance, the brake force relative to the respective brakes, i.e., the electromagnetic brake 17, the generator 25, the disc brake 30, the powder brake 40 and the oil damper 50. Namely, if the brake force of these brakes is smaller than an optimum range, the gimbal 14 is too swung or rotated to output the oscillation suppression torque (output). Also, if the brake force is larger than the optimum range, the gimbal could not be swung, and in the same manner, the oscillation suppression torque (output) could not be obtained and the oscillation suppression of the object to be controlled could not be attained. Fig. 12A shows an embodiment in which the oscillation suppression device is applied to a boat and Fig. 12B is an enlarged view showing a part A of Fig. 12A. Upon mounting the oscillation suppression device onto the boat 60, the gimbal 14a should be arranged perpendicular to the advance direction of the boat 60 as shown in Fig. 12B. In this embodiment, the two oscillation suppression devices are mounted but it is possible to mount one oscillation suppression device only. Figs. 13A and 13B show the arrangement of the respective devices according to this embodiment. In the case where these devices are driven, the gimbal shafts 14a and the gimbals 14 are swung, and the oscillation suppression torque is generated in the roll axial direction. Since the gimbal shafts are slanted, a component force is generated in the yawing axial direction (vertical direction). However, by mounting the two oscillation suppression devices for one set (two devices/one set) on the boat 60, the rotations of the flywheels 11 are opposite to each other to thereby cancel the component force of the yawing axial direction. Also, it is unnecessary to mechanically or electrically connect the two devices, and hence this arrangement is advantageous to be utilized in the limited space such as in the boat 60 or the like. The foregoing description of the embodiments according to the present invention is provided for the purpose of illustration only, and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

Claims: A oscillation suppression device for attenuating a oscillation of an object (10) to be controlled by a gyro torque (Tψ) of a control moment gyro having a flywheel (11) rotating at a high speed, characterized by comprising: angular velocity detecting means (18) for detecting a oscillation angular velocity (Φ) of the object (10) to be controlled; and control means connected to a gimbal shaft (14a) of said control moment gyro for controlling the angular velocity () of the gimbal (14) of said control moment gyro so as to absorb an external torque generated in said object to be controlled, in response to the oscillation angular velocity (Φ) detected by said angular velocity detecting means (18). The oscillation suppression device according to claim 1, wherein said control means includes an electromagnetic brake (17) connected to said gimbal shaft (14a) for braking the gimbal shaft, and an electromagnetic brake control means (19) for controlling said electromagnetic brake (17) in response to the angular velocity (Φ) detected by said angular detecting means (18). The oscillation suppression device according to claim 1, wherein said control means includes a generator (25) connected to said gimbal shaft (14a) for braking the gimbal shaft (14a), a variable resistor (26) connected to said generator (25), and a resistor value control means (27) for controlling a resistor value of said variable resistor (26) in response to the angular velocity (Φ) detected by said angular detecting means (18). The oscillation suppression device according to claim 1, wherein said control means includes a disc brake (30) for braking said gimbal shaft (14a), said disc brake (30) having a friction disc (31) coupled to and fixed to said gimbal shaft (14a) and another friction disc (32) coupled to a support frame (16a, 16b) that supports said gimbal shaft (14a) through gimbal bearings (15a, 15b). The oscillation suppression device according to claim 1, wherein said control means includes a powder brake (40) for braking said gimbal shaft (14a), said powder brake (40) having a magnetic disc (42) coupled and fixed to said gimbal shaft (14a), magnets (41) and a magnetic viscous material (44) sealed in a casing (43) that is fixed to a support frame (16a, 16b) for supporting said gimbal shaft (14a) through gimbal bearings (15a, 15b) and that surrounds said magnetic disc (42) through gaps. The oscillation suppression device according to claim 1, wherein said control means includes an oil damper (50) for braking said gimbal shaft (14a), said oil damper (50) having a stirring disc (51) coupled and fixed to said gimbal shaft (14a) and an oil (54) sealed in a casing (53) that is fixed to a support frame (16a, 16b) for supporting said gimbal shaft (14a) through gimbal bearings (15a, 15b) and that surrounds said stirring disc (51) through small gaps (55). A ship having said oscillation suppression device according to any one of claims 1 through 6, wherein said gimbal shaft (14a) is arranged in parallel to a pitch axial direction of a ship 60 for reducing rolling generated in said ship.

Inventors: HOSHIO AKINORI, TAKEUCHI HIROSHI, UMEMURA KATSUYA, HOSHIO, AKINORI, TAKEUCHI, HIROSHI, UMEMURA, KATSUYA, Hoshio, Akinori, c/o Nagoya Guidance &amp; Propulsion, Takeuchi, Hiroshi, Nagoya Guidance &amp; Propulsion, Umemura, Katsuya, c/o Nagoya Guidance &amp; Propulsion
Applicants: MITSUBISHI HEAVY IND LTD, MITSUBISHI JUKOGYO KABUSHIKI KAISHA
Application year: 1994
Main classification: B63B39
IPC codes: B63B39